As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT PREPARING FOR DEPARTURE, HAD SMOKE IN THE COCKPIT AND CABIN AFTER SELECTING APU BLEED ON. APU WAS INSPECTED FOR LEAKS AND DEPARTED WITH NO FURTHER SMOKE ISSUES. APU WAS INSPECTED AND TROUBLESHOT ON ITS RON MAINTENANCE, FOUND THE OIL TUBE PACKING OF THE OIL COOLER DAMAGED AND LEAKING. THE OIL COOLER TUBE PACKING WAS REPLACED AND BOTH LEAK AND OPS CHECK WITH NO FURTHER ISSUES.